The Botany of Iceland - 01.12.1930, Síða 69

STUDIES ON THE VEGETATION OF ICELAND
59
Some of the types of vegelation recorded from Lýngdalur recur
here, viz. mo, jaðar, mýri, and flói, while melar, mosathembur,
and geiri were not developed. In addition there occurred the flag
vegetation.
The Mo Vegetation. Cf. table 14 A—B.
In its broad features the appearance and floristic composition
of tlie mo around Björk corresponds to the above-described mo at
the liigher levels of Lýngdalsheiði.
The soil has the same knolly surface as that previously decribed,
but the knolls are less conspicuous on the slopes than on the flatlcr
parts. The composilion of the vegetation is likewise very similar.
Almost all the species found in the mo in Lýngdalur recur liere
and in approximately the same proportions. There are, however,
also typical dilíerences partly hetween this mo and that at the higher
levels, and partly between the various parts of the mo around Björk.
Three mo formations could be distinguished, an Eh'na mo, an
Arctostaphylos mo, and a Calluna-Empetrum mo. These three for-
inations differ in the following way. The Elyna mo is found on
the top of the many little mounds and hills which are covered
at the liigher levels of Lýngdalsheiði by the mosathembur vege-
lation, and have a comparatively thin snow-covering. 1 he Arc-
tostaphylos mo is found on the sunny slopes ol tliese hills
below the Elyna mo, and in the drier depressions among them.
I he snow-covering is somewhat deeper here and more persistent
than in the Elyna mo; it is the normal snow-covering in these
parls. Transitional between the Arctostaphylos mo and the jaðar
is thc third mo formation, the Calluna-Empetrum mo. Like
the Arctostaphylos mo, this formation has the normal snow-covering
in winter, but differs from the Arctostaphylos mo by being more
damp. Here the ground water has an appreciable influence on the
vegetation. In table 14 A tlie circling results for these three mo
formations have been tabulated.
Plants common to the three mo formalions and the mo at
higher levels and characteristic of the mo are, e. g. Empetrum
nigrum, Thymus serpyllum, Salix herbacea, Festuca rnbra, F. ovina,
Agrostis canina, Carex rigida, Juncus trifidus, Llizilla spicata, Poly-
gonum viviparum, Thaliclrum alpinum, Selaginetta setaginoides, and
Equisetum variegatum. Table 14 A shows the proportion in which
the various species occur and the good agreement between the